When flash illumination is used for the capture of an image, the pupils of a person in the image may appear to be red. This phenomena is often referred to as “red-eye”. This eye color defect is caused by light from the flash unit entering the pupil, reflecting off the retina, and exiting back through the pupil. Because light is partially absorbed by capillaries in the retina, the pupil appears to be red in the image. A person's photographically reproduced pupils which exhibit the red-eye phenomenon differ from normal pupils in that they appear red instead of their normal black coloration, and they are brighter. The probability of red-eye being observed increases the closer the flash unit is to the optical axis of the lens, so red-eye is commonly observed in images captured by a small camera with an integral flash unit. Red-eye becomes particularly noticeable when the image is enlarged. Thus, the red-eye phenomenon destroys many otherwise acceptable photographs. It is noted that this phenomena also occurs in flash photography of animals, although the characteristic color may not be red.
The phenomena of red-eye has been the subject of several patents. U.S. Pat. Nos. 5,130,789 (Dobbs et al.), U.S. Pat. No. 5,596,346 (Leone et al.), U.S. Pat. No. 6,252,976 (Schildkraut et al.), all commonly assigned and incorporated herein by reference, relate to the detection and/or removal of red-eye. U.S. Pat. No. 6,407,777 (DeLuca) is directed to a red-eye filter method and apparatus for a digital camera.
When an image is digital, it is possible to process the image with an algorithm which will locate areas suspected of being red eyes. If the algorithm is very accurate, only red-eye defects in the image will be detected and modified, often by desaturating the red area. The remaining portions of the image will be unchanged. However, present red-eye locating algorithms can be of limited accuracy. Often, user assistance is required to correct for red-eye.
In correcting for red-eye in images, the human eye-is located and the undesirable red portion in the eye is replaced with a more aesthetically pleasing color. As such, with user-assisted red-eye correction techniques, a user interface technique is needed to allow an operator/user to precisely identify a localized area of a digital image. Typically, the image is displayed and a point type location indicator is displayed (e.g., an arrow, cross hairs, touch, etc.) which indicates where the application “thinks” the operator is pointing. If a touch screen is used, one eye can be repeatably touched for further zooming in on the red portion of the eye upon each touch. Alternatively, a keyboard or other device (e.g., a joystick) is used to move the point type location indicator. The red portion is identified and a function is applied to the area to replace the red with another color.
This method of correcting red-eye requires constant human interaction, and as a result, is somewhat labor intensive. In addition, for the novice operator/user, this method may be confusing or not intuitive, causing the operator to be “satisfied” with a potentially unpleasing image rather than go through the process of understanding/learning how to remove the red-eye defect. In addition, a user may not recognize that red-eye exists in the image until the image is enlarged.
Accordingly, a need continues to exist for an automated method of informing a user that eye color defects exists, and a method of processing an image to correct for eye color defects which requires reduced input from a user so as to be less labor intensive and more intuitive than existing methods.